1. Field of the Invention
This invention relates to a tool for a coal cutting, mining or road cutting machine, having a round-shaft cutter with a cutter head and a cutter shaft, wherein a wear-protection disk is pushed on the cutter shaft, on an upper side of which the cutter head rests, wherein the cutter shaft is held captively in a receiver of a holding projection of a cutter holder in a direction of a center longitudinal axis of the projection but freely rotatable around the center longitudinal axis, and wherein the projection has a support surface, which extends at least in sections around the receiver, on which the wear-protection disk rests with an opposite surface and is supported on a support surface of the cutter holder, and wherein the cutter head rests on the upper side of the wear-protection disk facing away from the support surface.
2. Description of the Related Art
A conventional tool is known from German Letters Patent 37 01 905.809. A round-shaft cutter is rotatably seated in the receiver, embodied as a bore, of the cutter holder. The wear-protection disk is arranged between the cutter head and the support surface. During operation, the cutter head slides on the surface of the wear-protection disk because of the rotating movement of the round-shaft cutter. The wear-protection disk also rotates because of the frictional forces and slides on the support surface of the tool holder. Thus, wear of the wear-protection disk, as well as of the cutter holder, is generated. Because of the wear of the cutter holder, the wear-protection disk works its way into the support surface of the cutter holder. The area of the cutter holder adjoining the support surface is then subjected to considerable wear.
It is one object of this invention to provide a tool of the type previously mentioned, wherein the cutter holder is better protected against wear.
According to this invention, this object is attained with a support surface that extends transversely with respect to the center longitudinal axis of the receiver up to the exterior dimensional limits of an area of the holding projection adjoining the support surface. The wear-protection disk covers the entire, radially outwardly located area of the support surface with its opposite face.
As a result of the support surface of the wear-protecting disk, which is increased in comparison to conventional tools, the friction surface between the wear-protecting disk and the cutter holder is also increased. With this, the effective frictional forces are also increased, so that the inclination of the wear-protection disk to rotate on the cutter holder is reduced. This then results in a reduced wear of the cutter holder. Because the wear-protection disk extends up to the dimensional limits of the area adjoining the support surface, the wear-protection disk is prevented from working itself into the support surface. A dependable protection of the cutter holder thus results.
In one preferred embodiment of this invention, the holding projection is laterally formed on a base body of the cutter holder. When viewed in the direction of the center longitudinal axis of the receiver, the holding projection protrudes past the cutter holder. The support surface is arranged on the free end of the protrusion. The protrusion forms an area which adjoins the support surface, up to whose dimensional limits the wear-protection disk extends.
Thus, the protrusion of the holder projection is circularly embodied, and the support surface has a ring-shaped form.
So that the cutter holder is not worn to an overly large degree, in one embodiment of this invention the holding projection has one or several wear markings, which are arranged in the area behind the wear-protection disk. The wear markings can also be electrical detection units, which emit an electrical signal when the wear limit is reached.
However, it is also possible that indentations are cut into the protrusion of the holding projection, which extend on the circumference around the center longitudinal axis of the receivers and are used as wear markers, so that visual wear can be detected.
The material of the wear-protection disk can be of lesser hardness than the cutter head and the holding projection of the cutter holder.
In order to dependably dissipate the forces generated while cutting a road surface, the support surface has a diameter of more than 38 mm, preferably 44 mm.